This invention relates to a novel and pharmaceutically useful salt of chlorhexidine; more particularly, it relates to chlorhexidine di-2-pyrrolidone-5-carboxylate represented by the following chemical formula: ##STR1##
Chlorhexidine is an antiseptic and disinfectant, and is known by such name in The Japanese and British Pharmacopeias, in the form of its hydrochloride.
Of the known salts of chlorhexidine, the dihydrochloride, as well as the disulfate and diacetate, are sparingly soluble in water (cf. 1 g per 10,000 ml) and alcohols such as methanol and ethanol. Consequently, the digluconate is sometimes employed for pharmaceutical preparations because of its superior solubility in water and alcohols. However, it is hard to form crystals of the digluconate, even when the water solution thereof is concentrated to dryness.
An object of this invention is to provide a novel salt of chlorhexidine which is easily soluble in water and alcohols and is easily crystallizable at room temperature, and moreover, which has more potent antibiotic activity than the digluconate.
2-Pyrrolidone-5-carboxylic acid, namely L-pyroglutamic acid, is a known compound which has been used as a chemical reagent, for example, for the resolution of racemic amines (cf. The Merck Index, Ninth Edition, Item No. 7787).